This invention relates to gas turbine engines and more particularly to gas turbine engines which have only a single rotor that serves both as a radial compressor and as an axial turbine.
Simple turbine engines generally have two rotors or sets of rotors, one for compressing the intake air and the other for using some of the exhaust energy to power the compressor.
Large turbines with over 500 kW output power such as those in commercial aircraft and electric power generating stations use both a multistage axial compressor and an axial turbine. Long shafts necessary to accommodate two separate rotor blades in large state-of-the-art turbine engines are difficult to keep balanced and wear out. Shaft whip, vibration, and overheated bearings are common problems.
Either axial or radial turbines are employed in small turbine engines used for local power generators for backup and peak shedding. In these turbine engines, damage to rotor blades by hot exhaust temperatures is common.
The higher the firing temperature of a turbine engine, the more efficient it generally is. However, the firing temperature is limited by the ability of the turbine nozzles and blades to withstand the heat of the exhaust gases which must pass through them. Usually, almost a third of the air moved through a large turbine is used for cooling turbine blades rather than for combustion. Various high temperature materials and cooling schemes have been used to permit increased firing temperatures. Still, efficiency close to the theroretical maximum has not been achieved, the high temperature materials are generally expensive and rare, and the cooling schemes are generally costly and wasteful.
Most turbine blade and bearing cooling schemes involve use of any of a variety of patterns of cooling channels bored in the blades. For example, U.S. Pat. No. 4,522,562, issued to Glowacki and Mandet, Jun. 11, 1985, discloses a cooling scheme in which a turbine disc is equipped with a set of channels bored close to each of two sides of the disc and in conformity with the profile of the disc, with each set of channels carrying the cooling air of the turbine blades in order to superficially cool the disc.
There also have been developed turbine engines with turbine wheels or rotors which function both as compressors and turbine sections. For example, in the turbine described in U.S. Pat. No. 4,757,682, issued to Bahniuk, Jul. 19, 1988, fluid flow is redirected over the compressor section to effect multiple stages of compression and the same passages are used for both compression air flow and exhaust air flow. There is no suggestion that separate intake and exhaust passages could be interleaved in the same rotor.
U.S. Pat. No. 3,709,629, issued to Traut, Jan. 9, 1973, and related U.S. Pat. No. 4,070,824, issued to Traut, Jan. 31, 1978, disclose a gas turbine having a rotor serving as both compressor and turbine. The Traut turbine engine utilizes non-rotating arcuate members about the periphery of the rotor to direct the flow of combustion products against rotor blades to cause rotation of the rotor. The arcuate members help cool the turbine rotor blades, and also form passages for the subsequent exhausting of the combustion products. This is accomplished using a complex ducting scheme unlike that of the present invention.
There is still a need for lighter, more efficient gas turbine engines with simple design which can run at cooler temperatures and which are less susceptible to wear from multiple rotors on long shafts.
Therefore, it is an object of this invention to provide a single rotor gas turbine engine.
It is another object of this invention to provide efficient gas turbine engines which can run at cooler temperatures and which are less susceptible to wear from multiple rotors on long shafts.
It is a further object of this invention to provide single rotor gas turbine engines with less complex flow patterns.
It is yet another object of this invention to provide gas turbine engines specifically adapted for generation of electricity.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
To achieve the foregoing and other objects, and in accordance with the purposes of the present invention, as embodied and broadly described herein, there has been invented a turbine engine with a single rotor (rotating disk impeller) which cools the engine, functions as a radial compressor, pushes air through the engine to the ignition point, and acts as an axial turbine for powering the compressor. The invention engine is designed to use a simple scheme of conventional passage shapes to provide both a radial and axial flow pattern through the single rotor, thereby allowing the radial intake air flow to cool the turbine blades and turbine exhaust gases in an axial flow to be used for energy transfer.
In an alternative embodiment, the invention has an electric generator incorporated to specifically adapt the invention for power generation. In this second embodiment, an adaptation of the invention engine has magnets embedded in the exhaust face of the single rotor proximate to a ring of stationary magnetic cores with windings to provide for the generation of electricity. hi this alternative embodiment, the turbine is a radial inflow turbine rather than an axial turbine as used in the first embodiment of the present invention. Radial inflow passages of conventional design are interleaved with radial compressor passages to allow the intake air to cool the turbine blades.